Ok, the Big-Bad-Mama-Tama of a spoiler notwithstanding, this is how you do right by a car when it comes to carbon fiber...actually make everything out of carbon fiber.
Mansory SLS “Cormeum” Gets Carbon Fiber Body, SLR Style | AutoGuide.com News
Oh yea, and adding another 150+ horses doesn't hurt, either, though I must say I'd expect to achieve a lot more than a 200lb reduction in weight from a car as hefty as an SLS by going all CF with the body.